Synthetic lumber



July 1.5, 1930. A- F- BEMIS 1,770,507

SYNTHETIC LUMBER Filed Nov. 20, 1926 Patented July l5, E93

ALBERT F. IBEMIS, OF NEWTON, MASSACHUSETTS, ASSIGNOR TO BEMISINDUSTRIES, ING., OF BOSTON, MASSACHUSETTS, A CORPORATION OF DELAWARESYNTHETIC LUMBEB Application led November 20, 1926. Serial No. 149,764.

tions of walls, floors or roofs and are required to have a moderatedegree of strength.

The invention more particularly pertains structural to the formation ofcomposite lumber fromv4 loshcets or laminations of fibrous materialprefof high humidity. Preferably the fiber -board is provided with arough, irregular, or

semi-villous surface whereby it'may be firmly bound to the cementitiouscore and whereby the outer surface of the lumber may be adapt- 55 ed toreceive plaster, stucco, etc. In proportion to its strength and moistureresistant qualities it is comparatively light and may provide very goodheat insulation, while having better nailing qualities than either the60 conventional'ber board or the conventional gypsum slabs; andfurthermore, it may be easily worked or shaped by ordinary carpenterstools and may be handled, piled and shipped without requiring specialcare. 65

erably liber boardand frangible plastic or a The above and furtheradvantageous feacementitious material such as gypsum or the like.Heretofore it has been common in the art to provide thin ber boardswhich have had certain inherent defects, such as a tendency to warp,inability to resist moisture, exi cessive expansion and contraction,only moderate compressive and tensile strength, rather poor nallingqualities and the like. It has also been usual to provide slabs ofcementitious material, such as gypsum, with thin fibrous covering sheetsof flexible material, such as paper or cardboard; slabs of thischaracter having low tensile and bending strength, poor heat insulatingqualities, comparatively poor nailing qualities and a tendency to breakor crack easily, as well as being l particularly difficult to ship andhandle.

Furthermore, this material is comparatively.

heavy` in proportion to its heat insulating qualities and tensile orbending strength.

The present invention by combining the characteristics of the separatematerials indicated above provides a building material which has theadvantages common to both of the ty es of materialpreviously used, withthe disa vantages thereof reduced in degree or eliminated, thus beingsuited to a wide range of uses. The synthetic lumber disclosed herein,which comprises fiber boards located at either side" of a frangiblecore, has compartively good tensile and bending strength aswell as asatisfactory degree of compressive strength and does not have anobjectional 5e. tendency4 to swell or warp under vconditions ythematerial.

The composition lumber herein disclosed may be made of many suitablematerials, but preferably includes outer layers of fiber board so havingconsiderable inherent stiffness or tensile strength, for instance,material formed of felted vegetable fibers such as wood bers, ormaterial, which is made from bagasse fibers v which have been onlypartially cooked and a5 therefore retain substantially .all theiroriginal strength; these materials possessing numerous interstices orair cells so that their heat insulating qualities are comparatively'high and having rough, somewhat vlllous Sul- 'faces to permit'mtimatebonding with cementitious material. Rather than material of thischaracter a ber board having the characteristics commonly associatedwith other ordinary fibrous wall boards may be used.

Between the liber boards 1 of such a character, is poured or otherwiselocated plastic material 2, such as calcined gypsum, with or withoutsuitable aggregate; preferably pressure isthen applied to Ainsureintimate bond- -v ing of the bers and the plastic material. Formanyipurposes the thickness of the gypsum layer and of each of the berboards preferi ably may be substantially equal, but the thickness of thelaminations may be somewhat varied in order to adapt the lumber toindividual uses and installations. For example, in a case where heatinsulation is'particularly desired, the ber board, insulite or celoteXlayers may be made thicker, while in other cases where moistureresistance is a prime requisite, the inner gypsum core may be somewhatthicker. The outer ber board laminations and the gypsum core may beunitedvby Yany suitable means, but preferably in such a manner that arough brous surface of the board may firmly unite with the plasticmaterial as it hardens, so that a strong union or bond is formed betweenthe laminations of the lumber as designated by the numeral 8.

When it is desired to provide thick slabs or beams of this material, itwill ordinarily be found advantageous to use several laminations ofcementitious Amaterial and of ber board in the manner illust-rated inFig. 3

rather than using thicker layers of ber and gypsum..V

i omposite lumber of this type, which combines the separate advantagesof the materials found therein, will be found adapted to a much widervariety of purposes. In its preferred embodiment when manufactured ofmaterials such as referred to above, the outer layers will provideconvenient means for applying stucco, plaster, or the like, due to therough, brous surface which is a natural characteristic of this type ofber board; obviously, however, the lumber may be provided with a nishedsurface in any conventional manner, and in certain cases a gypsum slabmay form an outer layer of the lumber. The

lumber may be readily handledland shaped,

- posesses greater structural strength and betternailing qualities thanits component mai terials, and furthermore it provides satisfactory heatinsulatiomdoes not tend to expand, Swell, or warp appreciably whenexposed to high humidity or a high temperature and is comparatively reresistant, while it possesses the ability to absorb rather than reectsound waves.

I claim:

1. A sheeteof wall board comprising'outer layers of form retaining berboard and an intermediate frangible layer of cementitious material whichis bound by its inherent adhesive nature to the ber board.

2. A sheet of Wall board comprising outer layers of form retaining berboard and an intermediate frangible layer, said ber board having aroughened outer surface suitable for holding laster or stucco.

3. A s eet of wall board comprising outer layers of form retaining berboard and an intermediate frangible layer, said ber board providingheat-insulating layers.

4. Synthetic lumber comprising alternate layers of stiff, substantiallyform-retaining ber board and of cementitious material, said ber boardhaving rough surfaces bonded to the cementitious material, the outerfaces of .said lumber being formed by the ber boards whereby thecementitious material is protected against breaking.

5. A sheet of artificial lumber having relatively thick, light,form-retaining layers of cellular fibrous material having numerousinterstices, and an inner layer of cementitious material, said outerlayers constituting cush-` ening means for the cementitious layer, and

providing a board having good nailing qualities, said outer layers beingat least of approximately the thickness of.; said cementitious layer.

7. A sheet of artificial lumber havingY light, form-retaining outerlayers of cellular fibrous material having numerous interstices, and aninner layer of cementitious material, said outer layers constitutingcushioning and stiemng means for the cementitious layer, and providing aboard having good nailing qualities, said outer .layers being ofsubstanially the thickness of the inner cementiticus a er.

ySined b me at Boston, Massachusetts,

this ourth ay of November, 1926.

Y ALBERT F. BEMIS.

